Acoustic echo control involves cancelling or suppressing undesired echo signals that result from acoustic coupling between a loudspeaker and a microphone. Acoustic echo cancellation (AEC) or acoustic echo suppression (AES) may be used for this purpose.
AEC is a method where echo cancellation is accomplished by adaptively identifying the echo path impulse response and subtracting an estimate of the echo signal from the microphone signal. AES is a method where spectrum of the echo signal contained in a microphone signal is estimated, and the echo suppression is achieved by spectrum modification.
To estimate the echo signal, coefficients of an adaptive filter are adaptively updated to identify the echo path response. However, in the case that a doubletalk detector (DTD) detects a doubletalk (when a talker at the near-end of the microphone is talking in the presence of echo), usually the adaption of the adaptive filter is disabled to prevent that the near-end signal has a negative effect on the adaptive filter in terms of estimating the acoustic echo path.